It’s live action, although only in the loosest sense of the word, since almost everything in it except for the human actors is CGI. It’s also dark in tone, which is appropriate given Fincher’s back catalogue.
It’s worth pointing out that Fincher didn’t actually direct the trailer; that was left down to his special effects pal Tim Miller. But Fincher’s links to cult cinema are helping to generate plenty of hype.
More and more money is being pumped into producing trailers for videogames, particularly since the market now generates more revenue than the film industry. Could more movie directors end up working on this kind of content in the future? Almost certainly.